This is definitely not an okay situation. You should stop this relationship immediately. The problem is not that you are doing damage to your body, but to your emotional health. Sooner or later you will come to understand what your brother is doing to you is wrong. Once this happens you probably will have many mixed emotions that will be difficult for you to sort through. You may feel anger, betrayal, guilt, and may even blame yourself for what happened. It is important to remember that you were victimized and taken advantage of by your brother.
You need to tell your parents what has been going on. They may become very angry at first but hopefully they will come to understand that brother needs help and needs to be in specialized counseling for people who commit sexual offenses. You will also want to be in counseling to come to terms with the complicated issues that result from being sexually victimized by a family member. The rest of your family could also benefit from supportive therapy to get through this ordeal. There are many mental health professionals who specialize in treating incest and can help you and your family heal.
TeenHealthFX realizes that this is probably very scary for you. Once you tell what has been going on, there will be major disruption in the family. However this is the right thing to do. Unless you call attention to the situation now, it is going to cause more harm to you in the long run. If you feel uncomfortable approaching your parents first, talk to a school counselor, school nurse or an adult that you trust. The important thing is to tell someone so that you can begin the healing process as soon as possible.
If you would like more information or help you can call Rape, Abuse and Incest National Network (RAIN) 1-800-656-HOPE (4673) 24 hours, 7days a week. If you live in northern New Jersey and would like help finding a therapist you can call the Access Center from Atlantic Behavioral Health at 888.247.1400.